This invention relates to tube cutting and stacking and, more specifically, to a system for accumulating lengths of tubing cut from a longer-length workpiece and efficiently transferring the cut lengths to, for example, a stacking position in such a way as to cause minimal delay in the cutting operation.
Tubing is commonly manufactured in a continuous, high speed operation involving the steps of forming and seam welding metal strip stock. At the end of the operation, the tube is cut into manageable lengths of, for example, twenty feet. Fabricators typically purchase these lengths in bundles and cut them into shorter lengths according to the dimensions of the products to be fabricated from them. This is commonly referred to as a xe2x80x9cre-cutxe2x80x9d operation.
Re-cutting can be accomplished in several ways including pinch rollers, guillotine type cutters, and saws. Another method which is incorporated into this disclosure as a preferred method is disclosed by U.S. Pat. No. 4,635,514 to Alexander Borzym. Borzym discloses a shearing apparatus where a tube is held by two axially adjacent dies. As the dies translate relative to each other, the tube is parted along a shear plane defined by the mating faces of the two dies. A mandrel can be positioned within the tubing to prevent collapse of the tube walls during the shearing process. The advantages of this shearing method include speed and the elimination of the generation of debris and slugs associated with saws and guillotine cutters, respectively.
After a longer-length workpiece has been re-cut, each of the smaller lengths of cut tube is collected. One method of collecting short lengths of cut tube from the types of cutting devices listed above is to accumulate them on a rod-like element immediately downstream of the shearing location, i.e., the accumulator rod is positioned so that the cut lengths of tubing are loaded in series onto the rod until it is filled to capacity. Once the accumulator element is completely loaded, the tube shearing process must be stopped so the accumulator element can be removed, stripped and put back into position to resume the accumulation of cut lengths.
An object of the present invention is to provide an apparatus for accumulating lengths of cut tubing in such a way as to substantially reduce delay and loss of production time associated with stripping the accumulator element. This objective is achieved by providing multiple accumulator elements and moving these between accumulating and stripping stations in an efficient fashion. The multiple accumulator elements can, for example, be supported in parallel, spaced-apart relationship by movable support means such as a turret which is rotatable on command to move a loaded element out of the accumulating station as another empty element is moved in.
While this objective can be achieved using two accumulator elements, it is preferred to use three so that one element is in the accumulating or receiving station while another is in a stripping station and still another is in a waiting station. As a result, the shearing process is not unduly delayed by the translation, stripping and repositioning of a single accumulator element.
The present invention also provides clearing means for removing cut lengths from an accumulator element. When a full accumulator element is moved away from the accumulating station to a clearing or stripping station, a stripper can be engaged to clear the lengths of re-cut tubing from a free end of the accumulator element.
The present invention also provides collecting and stacking means to collect lengths of tubing stripped from an accumulator member and transfer them in predetermined numbers to a stacking station which may include a carton for shipping the cut lengths.
The aspects of the invention thus far described can be enjoyed in combination with any of the various types of re-cutters described above. The aspects of the invention described in the following section can only be used with a supported shear of the specific type described in Borzym ""514.
In the preferred form, the present invention also provides a sensor and control means to ensure that shearing only takes place when an internal die or mandrel is in the proper position. The accumulator element at the accumulating station abuts the mandrel and prevents downstream movement. A sensor can be positioned at the free end of the accumulator element to sense the presence or absence of the mandrel relative to the accumulator element. The sensor can emit a signal to a control means to stop the shearing operation if the mandrel is not positioned as desired.
The present invention also provides a sensor for sensing a quantity of lengths of re-cut tubing received by the accumulator element. The invention includes control means for controlling the displacing means based on the quantity of lengths of re-cut tubing received by the accumulator element. Specifically, when the accumulator element has received a predetermined quantity of lengths of re-cut tubing, the sensor emits a signal to control means to displace the accumulator element, then at the receiving position, to the clearing position. Contemporaneously, the displacing means moves a second accumulator element into the accumulating station.
Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.